1. Technical Field
The present invention relates generally to packaging of material using straps or bands, and in particular to bale banding systems and methods for banding bales that utilize adhesives to join or seal the baleband about the material being banded. More particularly, the present invention relates to an improved system and method for sealing pulpable balebands during the bale banding process where heat and moisture are required for the creation of an adhesive bond.
2. Description of the Related Art
Bale banding machines are known in the prior art that are designed to use cellulose-based bale banding straps in place of traditional metal banding to address the known problems associated with metal wire banding, such as the need to cut, handle and dispose of the metal banding after use. The use of cellulose-based bands allows the bands to be easily disintegrated, a characteristic which is particularly useful in the handling of wood pulp bales, since the banded bales can be processed directly without need for removing the band.
For example, U.S. Pat. No. 5,560,180, the disclosure of which is incorporated herein by reference, discloses a representative strapping station used in combination with a bale material conveyor. The strapping station is mounted on a movable platform and includes an encircling track for guiding a strap around a bale and a sealing head which contains a driving wheel to advance the strap in the track and, upon reversing the driving wheel, to tighten the strap around the bale. The strapping station further includes a clamping cam wheel, an adhesive applicator, a clamp to hold together two overlapping pieces of strap with adhesive applied until the adhesive has cured, and a cutter to sever the continuing strap and release it to be a tight band around the bale. The strapping station disclosed by U.S. Pat. No. 5,560,180 encircles bales of material with repulpable paper straps, whereby an adhesive is applied to the forward end of the strap, the adhesive-coated strap is overlapped with the continuing strap, and the overlapped portion is pressed until the adhesive is cured.
An improvement to the strapping station disclosed by U.S. Pat. No. 5,560,180 is described in U.S. Pat. No. 6,363,689, the disclosure of which is incorporated herein by reference, which discloses a representative banding machine having an improved bale banding adhesion method whereby the band is pre-coated or pre-impregnated with heat and/or moisture activated adhesive. Sealing of a band around a bale is accomplished using a thermoelectric heater tongue that is inserted between the inner faces of the overlapped band ends which are forced toward the heater tongue to heat activate the band adhesive. The heater tongue is then retracted and the overlapped, heat activated portions of the band are pressed together to secure the band around the bale. Since most adhesives are both heat and moisture activated, the foregoing band sealing technique also includes a water injector feature for wetting at least one of the ends of baleband during the band feeding operation and prior to inserting the heater tongue therebetween.
A problem encountered by such systems, however, is that the wetted portion of the baleband may become tacky, resulting in excess friction and possible binding as the band is fed through the close tolerance feed channel of the bale strapping track assembly. It would therefore be a useful improvement over the prior art to provide a baleband sealing system and method that eliminates such process inefficiencies. The present invention addresses such a need.